


A little Eggstra

by rehliamonster



Category: Undertale (Video Game)
Genre: Accidental Knotting, Begging, Come Inflation, Easter Eggs, Easterposition, Ectobiology, Egg Hell, Egg Laying, Eggpreg, Enthusiastic Consent, F/M, Hand Jobs, Knotting, Massage, Mating Cycles/In Heat, Mildly Dubious Consent, Miscommunication, Multiple Orgasms, Mutual Masturbation, Overstimulation, Oviposition, Praise Kink, Reader-Insert, Unexpected Pregnancy, Weird Biology, due to sexual hormones Sans isn't much better tbh, egg pregnancy, inaccurate birth, now get ready for the eggening, preggnancy, reader is a bit of an airhead, we had the preggening
Language: English
Status: Completed
Published: 2018-03-30
Updated: 2018-07-23
Packaged: 2019-04-15 23:51:27
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 10,086
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14152086
Author URL: https://archiveofourown.org/users/rehliamonster/pseuds/rehliamonster
Summary: You're appalled when you find that Sans has been hiding from you during his heat. Why didn't he come to you instead? He's your boyfriend, and you partially watched a documentary about monster heats, so you're practically an expert and ready to help him out!Right?Now with a followup chapter!





	1. Eggs will roll

**Author's Note:**

> The internet connection on my laptop crapped out so I'm posting this from my cellphone. Just a fair warning in case things get weird. 
> 
> Happy easter!

Finally. _Finally_ you found him.

“Sans? What’s going on here?” 

“oh no…”

He looks pretty unhappy that you found him here, sweating and blushing and not able to meet your eyes. 

Well too bad. You hope he feels guilty. 

Under normal circumstances you’d never be so vindictive, but this time you honestly can’t help it. Sans just vanished without a word, not even a note, and was completely unreachable via cellphone or any other means. No calls, no messages, nothing. And with Papyrus having gone on holiday just at the beginning of this week you couldn’t reach his brother either. You couldn’t reach _anyone_ for some reason, even though you really tried. Then you began pestering the police, but they didn’t really care about some monsters vanishing. The racism between the species still runs deep sometimes, and when you accidentally let slip that one of them was your boyfriend, there was no more chance they’d take you seriously. 

Three days you ran yourself ragged before it occurred to you to break open the lock to Sans’ secret laboratory in the back of the house. 

Only to find him here lazing around on the couch. 

As if you didn’t feel stupid enough already!

“Oh yes,” you snark at him. “Sans, I can’t believe you! Why on earth did you just vanish?! You could have at least left me a voicemail or something! I wake up one day and you’re just gone, do you have any idea how worried I was?!”

“gnnh… yeah… sorry…” 

“Don’t you dare groan at me like that, as if it’s some sort of big annoyance to you that your girlfriend was worried about you!” 

Honestly, you can’t believe this guy. What’s up with him? He normally isn’t like this! 

Sans might be lazy, but he’s a good guy and he treated you well in the almost one year you’ve been together. So this feels incredibly out of character for him. 

“i’m not… i don’t mean to… “ he interrupts himself, squirming on his spot on the couch. It’s the old one that used to stand in the living room, dragged up to the surface from the Underground into a new house and used for a couple of months before Papyrus put his foot down and demanded they buy a new one. Sans had then decided he needed a couch in his secret lab, and that was that. Or at least that's what he told you.

It’s a couch you have fond memories of, in general. Things have been done on that couch, down here, while the people in the house above were none the wiser. 

Right now though, you kind of hate that couch. 

Or rather, you hate to see Sans on it, wriggling back and forth as if he’s trying to get comfortable despite your scolding. Does he have no shame? What had he even been doing here all those days while you’ve been searching for him??

You take a closer look at him at that thought. 

Notice the sweat again, and the blush. The way his breath keeps hitching, and how he’s sitting with his knees pulled up against his ribcage, which still doesn’t hide the glow coming from his crotch. 

Wow. 

Really?

Seriously?!?

“Sans. Have you been masturbating,” you ask him dryly, unable to believe your eyes. 

“i… yeah… ‘m sorry…” He’s practically panting, his pelvis twitching as if looking for something to grind against while also trying to suppress the movement. “look, it’s… it’s a monster thing.”

“A monster thing?”

“y-yeah… didn’t wanna tell you.”

“But why?” 

You feel hurt. Have you ever given him the impression that you wouldn’t understand his monster biology? Or that you wouldn’t understand him if he told you that he needed some alone time? Sure, you want him to have sex with you, but you’re okay with it if he wants to pleasure himself without you every now and then! And you handled your surprise really well when you first saw his glowing, blue, magical cock, despite how strange the sight of it had been! 

“it’s called heat,” Sans groans, obviously having trouble keeping his faculties together. “it’s, uh…”

“Oh god, I’ve heard of that,” you blurt out. 

“you… have…?” This was definitely closer to a moan than a groan. Does he like the idea of you knowing about his heat cycle? You suddenly feel a bit warm. 

“Yeah!” you tell him, very eager to show him that you understand, that he doesn’t need to hide these things from you. “I heard about it when you first came out of the underground, when the news explained roughly how your bodies worked, with the magic and all. There was a documentary about it.”

It had been interesting to learn about, how magic and tiny light particles made up a monster’s biology, how when they ate magical food it would dissolve right away into energy and settle into their souls, how their souls functioned differently from human ones. The segment on monster heats had been pretty short as the makers didn’t want to be inappropriate towards a newly emerged species, but there had been the part about the collecting magic and… some other stuff. You had gotten a phone call during that segment, but you had gotten the most important things. You think. 

“uh…”

“They said it’s a magic build up that needs to be purged, right? And for most monsters that means having sex,” you continue, stepping closer and sitting down next to him, giving him a sympathetic look. “Sans, you could have said something. You know I love being close to you, right?”

He’s staring at you as if you’re some sort of cryptid, as if you’re a unicorn that suddenly stepped out of its forest and into his underground lab. There’s a definite edge of lust and desire in his eye lights, something physical in the way he gazes at you. You feel touched by his looks, like a tingle on your skin as you wait for him to say something. 

“but it’s… it’s how we make children,” he finally mumbles, averting his eyes again with shame. 

Oh, so that’s what his hangup is? 

Aw. Did he honestly hide down here and tried to deal with this all by himself just because he was worried about getting you pregnant? That's so thoughtful of him. Thoughtful, and completely unnecessary. 

“That’s fine,” you reassure him gently, placing a hand on his shoulder. After all, you’re on the pill. That always worked so far; you and him have had sex for a while now and he came inside you repeatedly and nothing ever happened, so you have no reason to be concerned about any unwanted pregnancies. 

“it… is?” he asks, visibly surprised. He actually sits up straighter and looks at you with a sort of baffled hope, intermingled with a rather lovestruck expression. And lust. He’s definitely, certifiably horny now. Even more so than before.

“Of course it is,” you laugh, thinking how cute he looks. “You’ve been coming inside me so often already, right? I wouldn’t have let you do that if I was worried. It’s all good.”

“oh damn…” he breathes out, scooting closer towards you until his body is pressed against yours. It’s clear that he’s more than eager to get close to you, to get this show on. “then… we can… you’re really sure about this? you wanna help me with my heat?”

The hesitant tone is gone completely. He sounds eager now, almost desperate, his pelvis already rutting against the side of your leg. His face is inching closer to yours until you can feel his breath on your lips. 

“Yeah,” you breathe out. A good fuck with him might be just the thing to get the lingering disappointment and anger out of your system. You know why he hid from you now and you understand, so all that’s left is getting over your own emotions. This is going to be a fantastic case of makeup sex, you can already tell. “I want you. I want _all_ of you.”

Sans is on you before you even properly finished speaking, moaning against you as he licks over your lips, practically begging for entrance. You grant it immediately, pleasantly surprised by his intensity and unwilling to torture him. It can be fun to tease him a little every now and then, but if you remember this heat thing right then he’s really needy right now, and you don’t want your frustration from earlier to cause you to be mean to him during the sex. That wouldn’t do. 

When Sans’ tongue touches yours it feels heated, almost feverish. He’s wrapping it around yours, massaging it and sucking on it as if his life depends on it, letting the heat seep into your sensitive flesh. Come to mention, his whole body feels like that now that he’s close enough for you to feel it. You run your hands over the bones of his arms and delight at the deep shiver that draws out of him, followed by a loud moan. 

He draws back, stares at you with hooded eye sockets. The pips of light in them are blown wide and trembling, practically blazing with energy. You’ve never seen him look so intense before and you feel a jolt of heat low in your belly. 

You like it when he looks at you like this. 

“turn around,” he growls. 

Shit, his voice has gone _deep_. 

Your breath hitches and you obey immediately, turning around on the couch until you’re on all fours, presenting your butt in his direction. Thoughts about him taking you from behind and rutting like an animal fill your brain, leaving your pussy slick with anticipation. 

To your great pleasure, it seems that you and him are on the same page here, because he can’t get your pants open fast enough before he pulls them down to your knees fast enough for the friction to burn your thighs, not bothering to undress you otherwise. The cool air of his lab feels cold against your backside, on the sensitive flesh of your slickened entrance. 

A deep rumble fills the room as he positions himself behind you. No foreplay, no licking or teasing or the slow, steady rhythm he normally takes his time building up for you. Just rough, hard, animalistic sex, running on instinct before anything else. 

You moan quietly, pushing back against him until you fill the head of his cock against your soft folds. 

You can’t wait to get on with it now either. It’s so hot to have him take you like this.

Sans pushes into you with a single, smooth movement and a long sigh escapes your throat, a vocalisation of pure breathless pleasure. He growls again and begins to move immediately, faster than he normally would. The slight burn of his rapid, frantic, desperate movements does nothing to diminish your lust, if anything it heightens the pleasure for you. 

The burn isn’t just from his movement either. He’s girthier than normal, you’re pretty sure. Shit, you like this heat thing already. You wish he hadn’t hidden for three days. The two of you could’ve had so much fun together. 

He grips your hips harder, slamming into you. The smacking sound of his bones against your flesh sound so hot to you, an audible reminder of his desperation for you. Angled like he is the head of his cock, softer than usual, keeps rubbing against your g-spot, stimulating you deliciously. Your moans get louder and louder. 

With the kind of pace he’s setting, it doesn’t take long before you begin to shiver, feeling the heat building into a concentrated point threatening to burst. 

“Sans, Sans I’m - “

“shit, yeah, me too, c’mon, c’mon…” he babbles, his voice cracking halfway through. 

You come with a hoarse cry and he follows you immediately after, crying out as his cock spasms inside you. You feel his cum gush inside you, heated and deliciously thick and you groan, involuntarily clenching around him, overstimulating your sensitive walls. 

Fuck, he feels so thick and hard still, even as he’s coming. 

And coming. 

He’s groaning deeply and his orgasm doesn’t seem to abide still, you can’t believe it. Even as your own haze of pleasure recedes, you can feel him continue to spill himself in you. 

“Damn, Sans, that's one hell of an orgasm,” you laugh, squeezing your vaginal walls deliberately to tease him. A wordless wail is all you get from him in return, shaky and filled with unabating lust. 

Personally, you wince. 

He's so thick inside you that squeezing him actually felt kind of uncomfortable just now. He feels almost swollen. You decide to pull away from him despite his iron grip on you. He can spill the rest of his cum on your tits or something, surely he'll like that too. 

Decision made, you pull forwards with a “Okay, that's enough now - “ only to immediately cry out when you end up pulling Sans with you. 

Shit, that stung!

“nnngh…” You feel Sans bend over and wrap his arms around you, pressing his rib cage against your back. You can feel him pant against your shoulder, his breath hot and wet against your skin. The shift causes his swollen cock to shift ever so slightly inside you, which draws another cry out of you. 

“Sans what is that?” you whimper, squirming underneath him. He's stuck inside you and his cock is still hard, pulsing against your walls as it stretches you out and continues to spill cum inside of you. 

“knotting…” he pants. 

You turn your head and stare at him in disbelief, but what you can see of his expression shows you a hazy eye light and a dopey grin. He's clearly not all there, still coming hard. 

“What?! Oh god,” you groan. “I didn't know you would knot inside me! Isn't that a dog thing? How long is this going to last?!” 

“dunno…”

Great. Sans isn't even capable of replying to you properly and you have no idea how long you'll have to hold out under him like this, with his cock stretching you out. This is freaky. He's tied to you so firmly that you can't even move on him to maybe try and get another orgasm out of this situation, you can't move away from him at all. Even reaching down to touch your clip would be difficult with how Sans is clinging to you. Although having another orgasm would probably be kind of painful anyway now that you think about it, if your muscles end up contracting around him while he's so huge inside you. 

Your lower belly gurgles, a feeling accompanying the sound akin to having drunk too much soda. Your vagina begins to feel oddly numb while you sense something inside of you beginning to loosen up. 

“What the hell?!” 

You bow your head down, looking between your arms to get a good glance at your belly. 

It's glowing blue, the same colour as Sans’ magic. 

He moans against your shoulder again, you feel another gush of fluid hit your insides, and the blue on your belly intensifies. You think you can see a faint bump developing from how much he's filling you up. Fuck, you didn't side up for this!

“Sans how much more are you going to pump iiieeeeeeeeh!”

The squeak escapes you automatically without any conscious input, as you feel something push against your walls, accompanied by another low moan from him. It's as if his penis is bulging in a slow wave, a thick coil moving upwards from the base of his cock to the tip. 

Then you feel something smooth and round and slimy connect with the flesh of you vaginal canal, something at least the size of your own fist. You realise that the sensation you felt wasn't from his cock but something inside his cock that made its way upwards through it and into you. 

It's pushed against your cervix, where you can feel a strain that you think should hurt much more than it does, and then with a sickeningly popping sensation you feel it sucked into your womb, settling against your front. 

The slight bulge of it is visible through your belly.

“Are you fucking laying eggs in me?!” you ask him incredulously. 

“sure… said it's how we… gnh… make kids…” he pants. 

“You didn't say anything about eggs!” you protest. 

Forget what you said about understanding his monster biology! You want no part of this!

A ragged moan is your only reply as you feel another egg travel through his cock towards your cervix. 

“gnnnnyou said you knew,” he whines while the egg is pressed through and into your womb. It really feels as though it should hurt, but it by now it doesn't. At all. You only feel the stretch of it, the weird sensation of something large moving through your insides and stretching you out. You wonder if his magic is numbing your pain, if you'll fold over later. 

Okay, maybe you did say that. But why didn't he clarify?! He can't just go ahead and put his span in you!

The second egg pops through your cervical opening and falls into place next to the first, the two of them rubbing against your insides, cushioned by the massive amount of fluid Sans pumped into you. 

“The documentary didn't mention this... “ you complain, squirming at the feeling, although you know that your statement must be wrong. 

But how were you supposed to know that the part of it that you missed would contain something like this?!

Sans’ cock looks human so of course you thought the reproductive functions would be the same too!

A third egg begins to travel through his shaft, more slowly than the others. You can feel it slide past every inch of muscle inside you, feel the precise moment it leaves Sans’ cock and the sticky-smooth surface touches your walls, feel it slowly press against your cervical opening, where it stops. 

“sorry, sorry,” Sans moans, apparently slowly getting what the problem is but incapable of holding back his own reactions. His pleasure is too strong, overtaken as he is by his heat. 

You're whining yourself, the third egg still stuck halfway in your vaginal canal and halfway in your womb. It's a strange sensation, as if you have been plugged close. 

And you can already feel a fourth egg following, the tell-tale swelling in Sans’ dick as the egg travels through it. 

“How many of these are you even going to put into me?” you groan, ending in a hiccup when the fourth egg bumps against the third without quite pushing it on, leading to both globes rubbing back and forth inside you, almost massaging your flesh. Some sort of sound is stuck in your throat as you process the sensation. Your not quite sure what kind of sound.

“d-dunno, it varies,” Sans manages to stutter out, sounding distracted and shaky. His arms are still wrapped around you but his hands are moving downwards, trailing over your skin until their cradled around your belly. He begins to lightly squeeze your abdomen, to rub it in a circular motion. 

It draws a surprised moan out of you when you can feel the eggs move inside you with his motions, jostled under his hands. His cock is pulsing inside you too, nudging the other two eggs forwards. 

“c’mon,” Sans mumbles, and from the sound of him you're not sure if he's even really talking to you directly, or aware that he's talking at all. “c’mon, take me, take them in…”

An upwards stroke of his hands and a pulse of his dick come together at just the right moment, in just the right way. The third and fourth egg make it through your cervical opening, rolling into your belly and squeezing in with the others. 

You cry out, it's a tight fit that makes your belly feel heavy. When you glance down you can see that the bulge has grown, the faint outline of the eggs visible through your stretching skin, still tinted blue with magic. It must be the magic making this possible at all, you decide, you're pretty sure skin isn't meant to stretch this much this fast. Or muscle and whatever else makes up your uterus, for that matter. 

“fuck yeah,” Sans groans, twitching as he feels the eggs roll into you. He's panting again, clearly more than turned on by this turn of events. His cock is pulsing harder again. 

You're panting yourself, drawing one heavy breath after another. Sweat is breaking out all over your body as your body tries to cope with what it's put through. 

You don't know what to feel, how to process this. You're on all fours with your boyfriend mounting you, stuck in this position, his unnaturally engorged cock knotted in your cunt. You're filled to the brim with cum, magical weirdo monster cum that's somehow seeping into your flesh and making it expand, and then on top of all that your boyfriend just laid four eggs inside of you and is clearly getting off to that fact. 

This is wrong on so many levels.

And he's not even _done_ yet.

“yeah, fuck, take it…” Sans is mumbling against you, dragging his teeth over the sensitive skin on your shoulder and your neck. 

A fifth egg announces itself with the same slow, rolling wave against your vaginal walls, this time being pressed into you more easily than the two before despite the fact that there's less space. Your belly feels tight and heavy, and Sans’ continuous massage of it allows you to feel each egg individually as they're pushed around in your womb.

“Ah…” 

The sound hangs in the air and for a second you want to refuse all knowledge of the fact that it came out of your own throat. 

Behind you, Sans begins to chuckle, a low sound that’s different from the way he would usually laugh, telling you that he’s still out of it. 

“yeah… you love this,” he grunts, squeezing your belly and pressing himself impossibly closer against you, until you can feel each individual bone of his on your back. “you love me filling you up.”

“W-what… I don’t,” you try to insist, a deep shudder going through your body as you feel a sixth egg coming up. 

“so good for me…” Sans pants, kneading your belly and nuzzling against your shoulder. “i love you so much…”

“Sans…” you moan, your breath hitching when the sixth egg pushes inside your womb. 

“yeah, that's it… ‘s good, isn't it. ‘m gonna make you a nice big clutch,” he babbles, rubbing his nasal bone against the shell of your ear while you struggle to keep another moan suppressed. “make you all nice ‘n heavy. they’ll grow inside you… incubate a bit until they harden, ‘n then i’ll help you lay them, ‘n when they hatch we'll have the prettiest babybones ever, you'll see.”

“I don't even know if I'm ready to be a mom,” you sob, although the thought of a tiny skeleton with Sans’ face warms a part in your heart you didn't even know existed. 

Fuck, you'll have to lay all of these stupid eggs, they'll all have to come out of you again, bigger and harder than they are now. 

You don't know why a high pitched sigh escapes you, bottoming out into a moan. 

“you're gonna be great,” Sans promises you, “you're so good, i love you, ‘m so happy you're gonna be carrying my eggs.”

You cry out loud when a seventh egg rolls up and begins pushing into you, it's too much and you feel so full and oversensitive already. You're sweaty and heavy and the eggs are moving in your belly as Sans keeps massaging it, grunting as if this is taking a great deal of effort out of him, as if he's working really hard here. 

Even though you're the one taking in all these eggs. 

“It's too much,” you whine, squirming under his ministrations, “I can't take another!”

“mmmh… yeah, you can,” Sans tells you. Is he even listening to you? “c’mon, for me…”

His fingers are hard on your stomach, kneading your with an even pressure that hits just the right spot between too soft and too strong. Slow, firm upwards strokes, and then something gives and the seventh egg slides in. You can feel it stretch you out more, can feel it press against you uterine walls and stretching them, can feel your skin expand just a bit more. It's a really strange feeling and you have no idea why you're moaning so loudly. 

“that's it, fuck, yeah,” Sans mumbles, running his hands over the outline of the eggs in your distended belly. 

“Sans, please,” you moan. 

Wanting him to stop, for thus to be over. 

Yeah. 

That's what you want. 

Definitely. 

“yeah,” he moans, just in time for you to feel the eighth egg coming. 

“Sans, Sans please, I… ah…” You shudder again, muscles trembling as the egg moves. It's a struggle to keep yourself relaxed enough that you won't squeeze your vagina around him, which would sting too much. It's just that feeling the egg travel upwards into you comes with so many overwhelming sensations. 

The way your vaginal walls get massaged as it moves up. 

The way its sticky-smooth surface feels against your sensitive flesh. 

How it pushes against your cervical opening, squeezing past the numbed entrance. 

How it pops into you only with greatest effort, distending your belly more. 

Eight eggs, rubbing against your insides with each motion of Sans’ massaging hands. 

A ninth already rolling up, and there's a weird double sensation coming along with it. It takes you a moment to realise that it's not just one egg, there's two this time, coming together. They seem to be stuck together because when they begin pressing into your cervical opening, there's still something firm rubbing against your cervix even when the first egg pops through and the second is still stuck outside. 

You and Sans are moaning together now, neither of you bothering to try and keep your voice down. There's a dripping sensation, slick fluid running down your legs. Inside you, you feel the same kind of slickness, helping the eggs move along. 

“yeah, that's it, help it along, you're doing great,” Sans groans, tugging at the skin of your stomach.

But the tenth egg is still stuck outside, not able to get in. 

“Oh god,” you whine, “oh my god, please, I can't… I need…”

“tell me what you need.”

“Make me come,” you beg, heat rolling through your body, the desire that slickened you up again finally impossible to ignore. You're stretched out and swearing and your crotch feels as if it's on fire and if you're being entirely honest with yourself, it's because you feel as though you've been edged for the past however many minutes it took to get those eggs inside you. 

Sans moans at your request, keeps one hand massaging your belly, but the other moves down between your legs and starts to stimulate your clit. It takes only two firm rubs and then you're screaming, your whole body spasming as an orgasm stronger than anything you've ever experienced courses through your body. Your convulsing around Sans’ cock and it stings because he's so big, but the numbness that his come induced in you keeps the worst edge off it away. Clamping down in his cock stimulates him enough to start crying out as well, hoarse now after he's been moaning for so long. There's a renewed gush of cum spattering inside you, coating your slickened walls. 

That's enough to finally push the tenth egg in, and the cum that follows it seeps between the other eggs, easing their movements as Sans keeps kneading your belly even through his own orgasm. The massage eases the strange sensation of your belly stretching out even further, something you're glad for. 

Your arms and legs are shaking now, and you feel ready to collapse. You don't think you've ever been so tired in your whole life as you are right now. The sweat on your body is rapidly cooling you down, causing you to shiver further. 

Sans is breathing a series of small, soft moans into your ear, warm puffs of sound tinged with deepest pleasure and satisfaction. He's still playing with your clit, slowly and lazily. 

It's too much, far too much, but instead of crying for him to stop you can feel your face scrunch up from the delicious overstimulation, mouth hanging open so much that drool begins dropping down onto the couch. 

“More,” you beg. “Please, I want more, Sans, I need more.” 

When an eleventh egg announces itself by the bulge in Sans’ cock, you begin to cry, moaning out loud again. 

It feels so good. 

You don't care anymore, you don't give a shit about how weird this is anymore, it feels good and you want more of it. 

Bending forwards, you rest your forehead on your arms, the position granting your tired arms some rest while also making it easier for the eleventh egg to slide into you, gravity helping it along with Sans’ movements. 

Your belly has grown big enough by now that Sans can't cradle it with a single hand anymore. Perhaps not even with two. You want him to try, to hold your bulging stomach with both hands, but you also don't want him to stop stroking your clit. He's cleverly moving around it now, not touching it directly to give you some reprieve, while also ensuring that you stay aroused. 

Another egg is coming. 

“twelve,” it bursts out of Sans in a ragged pant, revealing that you're not the only one who has ben counting along. “twelve already… you're so perfect… taking twelve… i love you…”

“I, I love you too, more, please,” you moan, even though the last egg isn't fully inside you yet. You're feeling greedy, wanting more of him, of him filling you up, of his hopelessly lovestruck words. 

But Sans grunts and his magic seems to obey your wishes, because the next egg comes and pushes the previous one along, popping them both into you together. Your stomach flares out further in one rapid movement, making you groan. 

You reach an almost meditative state, bent over as you are with your head resting on your arms. Your eyes are closed and so all you see is darkness. You smell the fabric of the couch, the dusty scent of fabric in a room with stale air. Your breath is heating up the small pocket of air you've created for yourself here. 

Like this, it's so easy to focus on nothing but the sensations. Sans’ bones digging into your skin at various points, his ribs on your back and his pelvis crammed against your ass. His hands on your belly and your clit, his femurs pressed against your thighs. It's as if he wants to cover and fill you completely, as if he's trying to meld into you. Being stretched out and the delicious rolling feeling of more eggs entering you. 

By now you've had enough eggs put into you to anticipate and appreciate the pattern here. Slide up, hitting your cervix, popping into your womb and stretching you out. Slide, hit, pop, stretch. Again. And again. 

Sans is mumbling words of praise against your neck, his speech slurred and barely comprehensible. 

“I love you,” you mumble back, because that's as good of a reply as any and you don't have enough mental presence yourself to say anything more coherent. 

Sans comes again after a while, spilling another gush of come onto your eggs. It feels warm and soothing on your cervix too, bringing back some sensation without allowing you to feel pain. It feels healing. Sans doesn't seem to have the energy for loud moans anymore, merely whimpering softly. 

And then you feel him deflate. 

The intense stretching sensation lessens. You almost feel sad, although you have to admit that while you were bent over you lost track a bit and you feel more than stuffed now. You can feel the skin of your stretched out belly against your thighs, you must be huge. It's probably good that it's over now. 

Sans’ cock finally shrinks enough for him to pull out of you, leaving you gaping open for a moment. You hear him flop backwards onto the couch with a groan, sounding just as exhausted as you feel. You allow yourself to fall to your side, barely making sure you don't tumble off the sofa entirely, and rest. 

You think you black out for a moment, because one second you feel comfortably satisfied and then the next you feel sticky all over while your bared lower body is cold.  
Sitting up, you pull your pants back up, only to discover that you can't close it anymore. 

Your belly is big enough to give the impression that you're several months pregnant already. It's pretty heavy too. 

“Oh man,” you blurt out, raising a hand up to poke it. You can feel the outline of some of the eggs, an impression that gets stronger when you rest the flat if your palm on your stomach and stroke over it. The movement jostles the eggs far less now than it would have previously. They must have settled somewhat while you were out, or your uterus contracted a bit or something. Thankfully, you still don't feel any pain from this, although the stretching sensation remains present. 

Damn, and you'll have to push them out. If you're remembering this correctly, Sans said that the eggs would grow, harden, and then you'd have to lay them. They're already as big as your firsts though, how large will they get? It'll probably be like giving birth several times over. How many eggs did you even end up with, ultimately? You somehow stopped counting at thirteen or something like that, but there were several more afterwards. 

You bite your lower lip. 

"Sans?” you ask out loud.

Looking over you see him lying haphazardly on the couch, knocked out from his exertion. You're not willing to let him sleep right now though, you have questions and you feel you have a right to ask them. His feet are right next to your leg, so you reach over and push a finger through a gap in his metatarsals, something that never fails to wake him up.

True enough, he startles awake with an undignified squawk, rapidly sitting up an staring at you with betrayal in his eye lights. You give him a moment, just to see if his heat is over and he's able to actually concentrate. Judging from the dawning look of realisation on his face, you think he can, so you decide to go ahead. 

You turn towards him, point at your belly, and take in his widening eyesockets as his gaze roams over the expanse of your heavy stomach. 

“wh - “ he begins. 

“I know there's over thirteen eggs in me right now,” you interrupt him, “not sure how many exactly but probably close to twenty or something.”

His eye lights shrink when you describe it like this, and wink out completely when you ask your question. 

“What the hell are we going to do with almost twenty kids?!”


	2. A little Scrambled

**Notes for the Chapter:**

> Several people wanted a continuation of this when I posted the first part and I got another request for it over on [My tumblr](https://rehlia.tumblr.com/) when I let people tell me what they wanted, so here we are. Enjoy some egg laying!!

You've been pregnant for about three and a half months now, and you're _huge_.

The eggs that Sans laid into you have been growing slowly but steadily in your belly, which continued stretching with support from Sans’ magic. Said magic had to be replenished frequently both to ensure your continued health and safety and to allow the eggs and the kids inside to grow properly. 

And by replenished you mean he needs to fill you up with his cum, ridiculously enough.

You hadn't been quite so eager about the prospect initially, which you found understandable considering what happened. But it drove Sans crazy. After impregnating you during his heat, his monster instincts have flooded him with a parental drive that demands he makes sure that you and the babies are well taken care of. You noticed an increasing desire to fuck him from yourself as well though. Since you know that what happened was in large parts a miscommunication and definitely also your fault, you cracked quickly and went back to having sex with him in spite of your initial unease. Besides, you missed fucking him. 

You could feel the eggs growing noticeably after each time. The two of you had discussed whether you actually wanted to go through with this pregnancy or not, after an initial giant freakout. He'd been really worried about this unplanned pregnancy and honestly so had you, especially with how crazy bloated your belly was. He assured you that it would be physically safe for you immediately of course. His magic would protect you so the rapid stretching you went through wouldn't hurt you. When the two of you calmed down a bit and you asked him for more info, he also told you that most of the eggs would probably not be viable in the first place, as was common with monster eggs. That helped the two of you decide; you would carry them to term, lay them, and then simply adopt most of the surviving kids out. You and Sans would take care of the remaining one or two. You had decided that you were ready after all. If you were at each other's side, you could do this. 

Images of peaceful family times kept floating through your mind while your pregnancy progressed. Sans as a loving father, you as a doting mother. Your children, adorable little hybrids, looking up at you with gleaming, curious eyes as you taught and guided them with a gentle hand, patient and kind. And all the baby stuff you got to buy! Adorable little cots with ruffled decorations, tiny baby clothes, the cutest little crib bedding!

It would be awesome!

By now, you're looking forwards to having the kids here, and not just because you're so big that you can hardly move anymore and want to go back to being mobile. According to Sans, monster pregnancies would take between three to four months depending on species, then the eggs would be laid, and then they'd need to incubate outside for another month or two before they'd be ready to hatch. That means you could be due any day now!

You and Sans had immediately alerted Toriel about your pregnancy of course and she had checked up on you regularly to ensure you're healthy, to see if the pregnancy was progressing properly. She'll be on standby for the laying of the eggs too, in case anything goes wrong. But ideally it won't and you and Sans will be alone. The process tended to be intimate according to him and it was hard for monster parents to accept others being there when they laid eggs. 

You have to admit you'd rather not have anyone there either. The idea of Toriel looking at your private bits while you pop some eggs out doesn't really appeal to you, as nice as she is. 

It's a calm evening, you and Sans are watching a movie while Papyrus is visiting Undyne, when you notice it. 

An odd sort of squeeze and tingle in your cunt and belly. 

At first, you squirm and merely wonder if you need more of Sans’ magic. Sometimes your body would let you know that the eggs needed more magic by making you horn for your boyfriends cum in you. You quickly notice this feels different though. You do feel horny, but you definitely don't want anything inside you right now. Quite the contrary. 

Your belly feels tight all of a sudden, the muscles contracting without your input, and you notice a sense of wetness between your legs. 

“Oh, uhm.” 

“hm?” Sans looks over to you, relaxed and lazy as always. He's gotten real comfy on the couch, slouching in the pillows and enjoying the fact that his brother isn't here to scold him for it. His sockets are half open and his eye lights wide with comfortable happiness. 

“I feel wet and crampy,” you tell him. “I think it might be starting?!”

In less than a second, he's sitting up and hovering over you, hands over your belly while not quite daring to touch you. You've never seen him move so fast. 

“oh shit. you sure? should i fetch the - “

You squeak when a sudden gush of fluids spatters out of your crotch, wetting your legs and the couch. 

“...towels,” Sans finishes. “shit. i’ll go get them.” 

He pops away without bothering to wait any longer. 

Oh damn. It really is starting. Breathe, you tell yourself. It's gonna be fine. Just some eggs coming out of you. 

Holy shit, you'll have eggs come out of you. 

No, no, it's fine, focus on the cute babies that will hatch out of them. It's gonna be fine. 

The pressure in your belly increases and you can't help but start to huff. Your cunt feels hot, the slickness spread on it still tingling like mad. You feel a strong urge to reach down and scratch it, or rub it, just to get some relief. Your belly is too big though. You can't reach down there by yourself. 

“Hnnnngh…” you sigh, squirming with the discomfort. The couch is already ruined by your fluids, so you sit up and try to grind against the upholstery, hoping to get some relief from the friction. Your pajama pants prevent that though. You should probably take those off anyway. 

You're in the middle of trying to wiggle your way out of them, hindered by your massive bulge, when Sans returns with his arms full. Towels, lubricant, water, snack foods; it seems he tried to gather everything you might need in one round so he wouldn't have to leave you alone again. He even brought some human medicine too, in spite of the fact that his healing magic should do the majority of the work. 

“okay, okay, let me… let me set this up real quick,” he stutters, throwing you a worried glance when he notices how uncomfortable you are. 

“Saaaaans,” you whine. “It's itchy!”

“that's good, that's normal, i’ll help you in are second!” he promises, starting to lay out the towels on the floor. 

You keep whining, but at least you finally manage to get rid of your pants. Sans helps you down onto the floor so you can get comfortable on the towels. According to him and Toriel, laying the eggs on the floor is the safest option. Like this, neither you nor the eggs can call if you end up moving around too much. 

“ok. now, let's see,” Sans says, crouching down to take a look at your crotch. He thankfully put his fingers on it to spread your lips a little, and you immediately grind against them and groan when that helps alleviate the tingling itch in it a little. 

“Fuck, that's better,” you sigh. 

“looks like you're not quite ready yet,” Sans comments, sitting up again. 

“So we have to wait more?” you wonder. “How long is this going to take again?”

“it varies,” Sans reminds you. “every monster is different. or, uh, any human too i guess. but, we shouldn't wait much longer. the eggs are gonna come soon now that the fluid’s leaked out. i’ll help you along.”

“That's - oooooh…” 

His hard fingers begin working on your cunt, pressing against your lips with long, even strokes. That's the stuff. This feels so good with how much your flesh is tingling there. Sans had told you that having to help monster eggs out of the carrier via massages and sensual touches was a common process, so maybe this is just how it's meant to go down. You grind against him gratefully, even though you don't manage to move much with how heavy you are. 

Sans increases the pressure and uses his other hand to still your twitching hips. 

“shhh, you don't gotta move around so much. i’ll take care of ya.”

“Hnn… okay…” 

Man this feels… really good. Your legs spread open wider, falling to the side. You put your hands on the floor behind you and lean back on them for extra stability. Like this, spread open and stabilised with Sans working between your legs, you don't feel quite as uncomfortable anymore. He's taking good care of you. While one of his hands keeps massaging your cunt, the other wanders up from your hips to your belly, feeling the eggs there underneath your skin. 

The pressure in your belly hasn't increased much since this began, but having his hand there still reminds you of how tight things are feeling there all of a sudden. 

“Sans…” you groan, “are they going to come out soon?” 

“yeah, pretty soon. we got this, no worries,” he assures you. His fingers on your cunt shift and change their ministrations, still pressing against your cunt, but also caressing the lips. He then brings his fingers into your opening. 

“Hannh…”

“sounds like you're not that uncomfy,” Sans chuckles, carefully working you open with his fingers.

“I… I didn't think it'd be so much like… hah… like sex…” you moan. 

“why?” he looks at you with a mixture of curiosity and mischief. “makes it easier to get them out if you're aroused ‘n slick. ‘s why we monsters say it's intimate ‘n private.”

You almost want to ask what monsters do if strangers do need to come in at some point in the process, but then you decide you don't actually want to know. You'll just hope that all goes well for you and the two of you can stand alone. 

You whine when his fingers curl inside you, stroking your sensitive inner walls. He's carefully alternating between scissor in his fingers to work you open and stimulating your g-spot to make sure you're as wet as you can be. You feel a heated tension building in your cunt and your abomen. It's torture of the best kind, but still torture.

“I wanna come,” you whine, your hips twitching again now that you're getting closer.

“come for me then,” he tells you, his voice a low whisper. “it’s okay.”

His ministrations speed up and his thumb grazes your clit, sending you over the edge. 

A deep moan tears itself out of your throat and you feel your body shake. The tight feeling on your belly intensifies and more slickness gathers between your legs. Your body shakes again and the pressure in your abdomen shifts lower. You feel something deep inside you stretch and a strong downwards force, as if gravity suddenly increased on your belly and vaginal canal. You're ready. 

It's happening. 

You can feel the first egg drop, stretching you out further than you've ever been before. It's a strange sensation and not exactly one you'd describe as comfortable, but the gush of magical fluid you expelled when this started seems to have dulled the potential pain of this just like it did when Sans impregnated you, so at least you're not hurting. It's just the pressure in you belly and the insane stretching sensation as the egg slowly comes downwards. 

“Oh god… it's so big…” you groan. 

“i know. ‘s okay. you can do this,” Sans soothes you, now kneading your belly harder while the ministrations on your clit have let up. His massage is helping the egg move. 

“Hnngh…”

You do your part when you feel the egg low in your vagina. You begin pushing, straining your muscles to make the egg come out. It's definitely harder than what you felt when Sans laid the eggs inside of you, the sticky-soft surface now hardened to a smooth and even shell. 

“Ah…” 

Sans grins at you in a knowing way when you can't help but moan as the egg descends. 

“not bad, huh?” 

“F-feels like some sort of toy,” you admit. It's true. The perfectly even surface of the egg massages your inner walls deliciously as it comes out. You can feel it at your entrance now, spreading your opening. 

“heh. glad to hear it's as pleasant for humans as it is for monsters,” he chuckles. “ ‘n you're doing so well too. i can see the first one already.”

His fingers lower themselves until you feel him trace your opening as the egg continues to stretch it. You moan deeply and instinctively push harder. The egg slides forwards, stretching you to the point of near discomfort, and then with a sudden pop it slides out completely, right into Sans’ hand. 

“there you are,” Sans croons. His eye lights and expression are soft as he holds up the egg for both of you to see. It looks as smooth as it felt even as it is still covered in magical residue and your juices. The shell is the same soft blue as Sans’ magic and opaque, but you can see are glow emanate from within. 

“Is that…?” you wonder. 

“yeah. that’s the soul glowing,” Sans confirms. “this one's viable.”

You look at the egg with winder and experience a sudden rush of awe and pride and love. 

You made this.

Your body helped create this miracle, a little soul glowing within the protective confines of the egg Sans had laid in you. It grew inside you and fed on your soul energy until it became a little something of its own. It only needs to incubate a bit more and then it will be a baby, your and Sans’ baby, your cute little child. 

“Wow,” you sigh as tears gather in the corners of your eyes thanks to all the emotions. 

“i know,” Sans tells you, similarly amazed. He pulls out another towel and cleans the egg, then sets it down carefully in a little nest of pillows and blankets he creates for it. 

You can already feel your stomach contracting again while he does this, the next egg sliding down into your canal. 

“Oooh…”

“next one already?” he asks you, bringing his attention back to you. “you're going fast.”

“I can't… mmmmh, help it… it's just… ah… happening…” you stutter, interrupted by your own moans. You're louder this time. 

Now that the first egg has come out, the stretching sensation of the second egg doesn't feel so unusual anymore. Instead, you can focus on the pleasantness of the stretch and the inner massage, leaving you squirming and moaning. 

“How is… mmmh… how is this so good?!” you whine, panting when the smooth glide of the egg sends waves of heat and sensation through your crotch. 

“mobster scientists think it's to encourage us to breed more,” Sans explains. “if it's more pleasant then monsters will want to have more sex and give birth more often, whereas the ones for whom it's painful bred less often and slowly died out.”

That's a logic you can't argue with. As you groan from the intense pleasure of the second egg crowning, you can't help but feel that in comparison to this, human birth seems to have some major design flaws. Not that you ever experienced human birth, but still.

You push and your breath hitches when the second egg pops out, leaving you stretched out and empty in a way you don't want to be right now. 

“another viable one,” Sans tells you excitedly. 

“Mmh… how many are gonna be viable again?” you ask, already massaging your own belly to help the eggs along. You really want them out now, and unlike earlier when you only wanted that so you wouldn't be heavily pregnant anymore, you now want to lay them because it feels so good. 

“about a quarter to a half is what's normal for monsters, since the eggs feed on soul energy and there's only so much we can sustain” Sans tells you. “so for you that should be anywhere between five or ten.”

“Right…” you sigh, grinning when you feel the next egg drop. It's a good thing you and Sans had found so many potential adoptive parents among the monster population early on. 

Toriel herself had immediately volunteered when she heard about your pregnancy. She had been thinking about adopting another child or perhaps even two so Frisk could grow up with siblings while they were still young, and she felt that this occurrence was a sign to go through with it. Dogamy and Dogaressa had volunteered, 01 and 02 were ready for their own family now, a lovely rabbit couple had asked, a single asexual Night Knight. Papyrus had volunteered to help you if more than one kid remained. You feel well prepared for this. 

With your hands on your belly, you feel exactly when another contraction hits you and the next egg slides down. It enhances the pleasure for you, honestly. You’re already looking forwards to pressing this one out and you lick your lips a little as you sigh. You can hear Sans laugh at your pleased expression, but you’re too focused on yourself to care right now. 

Deliberately contracting your muscles, you push the egg into your canal and moan when you feel it's smoothness on your flesh. You're going hard on this one, pushing and pushing, making it move down inside you much faster than the first two. The pressure increases due to your muscles contracting, so that you feel the stimulation of it much stronger. 

“Ah, fuck…!” you cry out as an orgasm hits you. The egg practically shoots out of you, giving Sans some trouble to catch it. 

“jeez, slow down -”

You don't listen. The spasms of your orgasm have pushed another two eggs down, coming together. The sensation is so intense that you have no mental space left to focus on anything else. Several high pitched whines escape you, brief and breathless. Your vaginal canal feels like it's going to burst at any second, you're so stretched out, but thanks to the magic it feels nothing but good. Powerful pleasure rockets through you, pushing your right into yet another orgasm. 

It's a chain reaction that you have no way and no intention of stopping. Each orgasm makes your body contract harder, and each hard contraction pushes more eggs down to make you orgasm. You scream and moan with wild abandon, hips grinding and muscles twitching, as the process spirals into a lust-fuelled haze. Sweat builds on your body, your head falls back against the couch and your eyes roll back. You might be drooling a bit. Your cunt feels desperately overstimulated by now, you think you can hear Sans shouting, you can't bring yourself to care. 

Some of the eggs come alone, others come in pairs, just like when they were laid in you. But all of them squeeze through your opening at a rapid pace. The swift change between being filled and being empty reminds you of sex, of being penetrated by Sans’ cock. The thought of that, and the memory of his knot in you while he laid all the eggs you're now pushing out, is delicious to imagine right now. Just like when you were bred, you fall into a sort of trance, a place where your thoughts at completely empty save for the blaze of your toe curling orgasms, and the thoughts of the eggs, and of Sans. 

By the time you manage another clear thought, you feel hoarse and tired. Cooled sweat is sticking to your skin, a trail of drool has dried on your chin and your muscles are still twitching with the aftershocks of your multiple orgasms while also shivering from sheer physical exhaustion. You feel stiff from sitting ok the floor for however long this took, and weirdly empty inside. So the eggs must be all out, right?

Lifting your head to look down at yourself takes way more effort than it should bur when you manage, you find that your belly is indeed flat again. The blue glow on it that the eggs emitted isn't there and you see no scars or other marks hinting at how abruptly the size of your belly has changed over the past couple of months. It seems as though Sans’ magic protected you fully from the effects of the stretching. That’s probably a good thing. If it hadn’t, your skin might have been seriously damaged with how quick it has been. You sigh in relief at seeing that you came out of all of this unscathed. 

“uhm…” 

You look up, needing to blink a little. It’s easy to get lost in thought due to how tired you are, especially when you look down. You could’ve dozed off like that, and maybe you were about to amidst all of your belly related ponderings. Sans’ little noise really pulls you out of it here, although you’re immediately glad about it of course. You want to know what the eggs look like. 

“Sorry… that was a bit intense,” you excuse yourself. Your voice sounds scratchy; you really need a drink. On top of that, your words sound a little slurred, probably because you’re so tired and overstimulated post-multiple-orgasms.

“y-yeah, don’t think i’ve ever heard of something like that,” he stutters. Now that you take him in, you can see that he looks awed, worried, overwhelmed and shocked all at once. 

“You didn’t? I thought it was supposed to be pleasant,” you argue, somewhat surprised at his reaction. 

“well, yeah, but not like that! you looked like you completely lost control, and then they all just… they came out so fast,” he tries to explain, gesticulating with his hands.

“Hah… I noticed… “ you giggle. It’s hard to stop once you start; it’s as if you’re high. Maybe you are, on happy orgasm hormones or something. 

“uh… yeah, anyway… you alright? no pain?” Sans asks. “i started healing you at some point just in case but you didn’t seem hurt.”

“Nah, it felt… mmmh, that was the best orgasm _ever_...” you sigh, and even you notice how damn pleased and satisfied and happy you sound. 

“heh, good for you?” It seems as though Sans isn’t quite sure what to do with your bliss. “uhm…”

“And there were so many… “ you moan. “One after another. It felt as if I was exploding. It was overwhelming, but so good…” You pause and then say something that you never would have thought to come from your own damn mouth. “We don’t know some other couples who desperately want to adopt, do we? Because honestly I wouldn’t mind doing that again all things considered.”

It’s perhaps unusual but, come on, that was the most intense pleasure you ever experienced. Is it any wonder you feel hooked? 

“about that,” Sans says, now breaking out in sweat. “that… we, uh. well. about the eggs.”

“Oh! Yeah, of course, sorry, I’m still a bit…” you smile and vaguely gesture to your head, trying to convey how out of it you feel after that intense orgasm, the exhaustion of laying the eggs, and everything. “Of course we have to deal with this clutch first. How are they? How many are there even? And how many came out viable?” 

You’re really curious now, considering you lost it immediately after the second egg. You can’t even immediately see them in the little nest Sans made for them. He’s sitting in front of them from what you can tell, blocking the view. 

“uh… well, see, i told you that the eggs feed on the soul energy of the parent, right, and, the thing is, human souls are very strong, and - “ 

“Sans… how many?” 

He gulps. 

“nineteen.”

“And how many are viable?”

The two of you stare into each other’s eyes, both dead serious now. It’s an easy question. It should have an easy answer. For Sans to be evading you like that means something must have happened. 

But.

If you’re honest with yourself, you already know the answer in your heart.

“all of them,” Sans says. 

“All of them,” you repeat.

“all of them,” Sans confirms. 

For a moment, neither of you makes a sound, or even dares to twitch. As if you’re locked into a mexican standoff. In the end it’s you who breaks it.

“Oh hell,” you groan, your head falling back once more. “Where the hell will we find that many parents?!”


End file.
